The 3rd Generation Partnership Project, 3GPP, is responsible for the standardization of the Universal Mobile Telecommunication System, UNITS, and Long Term Evolution, LTE. The 3GPP work on LTE is also referred to as Evolved Universal Terrestrial Access Network, E-UTRAN. LTE is a technology for realizing high-speed packet-based communication that can reach high data rates both in the downlink and in the uplink and is thought of as a next generation mobile communication system relative to UMTS. In order to support high data rates, LTE allows for a system bandwidth of 20 MHz, or up to 100 MHz when carrier aggregation is employed. LTE is also able to operate in different frequency bands and can operate in at least Frequency Division Duplex, FDD, and Time Division Duplex, TDD, modes.
In an UTRAN and an E-UTRAN, a User Equipment, UE, or a wireless device is wirelessly connected to a Radio Base Station, RBS, commonly referred to as a NodeB, NB, in UMTS, and as an evolved NodeB, eNodeB or eNB, in LTE. A Radio Base Station, RBS, or an access point is a general term for a radio network node capable of transmitting radio signals to a UE and receiving signals transmitted by a UE. In Wireless Local Area Network, WLAN, systems the wireless device is also denoted as a Station, STA.
In the future communication networks, also referred to as the 5th generation mobile networks, there will be evolvement of the current LTE system to the so called 5G system. The main task for 5G is to improve throughput and capacity compared to LTE. This is in part to be achieved by increasing the sample rate and bandwidth per carrier. 5G is also focusing on use of higher carrier frequencies i.e., above 5-10 GHz.
In LTE, “tracking” is a functionality which supports locating the UE. The network is broken down into Tracking Areas, TA. The network configures a UE with one or more tracking areas. This allows the network to locate the UE within a certain defined region. When the UE enters one tracking area which is not in the list provided by the network, the UE performs a tracking area update. This update assists the network to update the UE location information. In LTE the tracking area is indicated via the system information, SI, which is regularly broadcasted in the cells.
The 5G concept does not use the LTE system information, SI, concept. Instead, a new concept “System Control Plane, SCP” is introduced to enhance the functionality. The SCP concept is based on a node transmitting a System Signature Index, SSI, which points to an entry in the Access Information Table, AIT. The AIT is a collection of the different system information configurations. These configurations should only carry, in principle, information related to the network access e.g. random access parameters. In other words, the AIT should not contain any location information.
To support dormant mode mobility and paging, the 5G concept includes a separate “tracking Radio Access Network, RAN, area”, TRA, entity with associated signals to convey the TRA identity. The signal must be detected by wireless devices waking up from sleep after potentially long DRX periods and carry information about the tracking area identity and system frame timing, estimated 30-40 bits. Subsequently the wireless device might need to detect other control signals used in the initial access procedure, where the same support for synchronization as for TRA reception is required.
There is thus a need for providing sync support for control signals that does not incur unnecessary overhead associated with coarse synchronization.